The present invention relates to a substrate processing apparatus, which processes substrates, e.g., semiconductor wafers, solar battery panels.
In ordinary methods of producing electronic devices, e.g., semiconductor wafers, solar battery panels, a step of forming films by chemical vapor deposition, etc. and a step of plasma etching are performed as ordinary processing steps. The inventor of the present invented an apparatus which is capable of continuously performing the steps so as to process flat works, e.g., semiconductor wafers (see U.S. Pat. No. 6,007,675). The apparatus is shown in FIG. 6. The apparatus comprises a processing chamber 20, in which plasma-vapor deposition is performed to works 10, e.g., semiconductor wafers, and load lock chambers 22 and 24, which are connected to the processing chamber 20 so as to feed the works 10 into and carry out them from the processing chamber 20.
The processing chamber 20 includes six stages A-F. The stage B, which faces the load lock chamber 22, and the stage A, which faces the load lock chamber 24, are used as stages for transferring the works 10; the stages C-F are used as processing stages.
Six rotary arms 26, which support the works 10 set in each of the stages, and a rotating mechanism, which intermittently circularly moves the rotary arms 26, between the stages, in one direction (in the clockwise direction in FIG. 6), are provided in the processing chamber 20. The rotating mechanism includes an elevating mechanism, which vertically moves the rotary arms 26 between an upper position (a conveying position for conveying the works 10), which is located above setting plates of the stages, and a lower position (an evacuating position for setting the works 10 onto the setting plates), which is located under the setting plates.
The load lock chamber 22 stores the works 10 to be fed into the processing chamber 20; the load lock chamber 24 stores the works 10 processed in the processing chamber 10. A holders 28, in which many works 10 are vertically arranged with narrow spaces, are set in the load lock chambers 22 and 24. In the holder 28, a plurality of supporting bars 28a are vertically arranged at regular intervals. Each of the works 10 can be sidewardly putted into and taken out from each of the supporting bars 28a. The holder 28 is synchronously moved, in the vertical direction, with feeding and carrying out the works 10, by a lift mechanism.
Open-close plates 30 are respectively provided to openings of the load lock chambers 22 and 24, through which the works 10 are fed and carried out. Gate valves 32 are respectively provided between the processing chamber 20 and the load lock chambers 22 and 24.
In the apparatus shown in FIG. 6, the open-close plate 30 of the load lock chamber 22 is opened, and the works 10 are supplied to the holder 28 set in the load lock chamber 22. Then, the open-close plate 30 is closed, and inner pressure of the load lock chamber 22 is reduced. When the load lock chamber 22 reaches prescribed degree of vacuum, the gate valve 32 is opened so as to feed the works 10 into the processing chamber 20. A transferring mechanism, which has a hand 34 for transferring the works 10 between the load lock chamber 22 and the processing chamber 20, is provided in the processing chamber 20. The transferring mechanism takes out the works 10, one by one, from the holder 28 of the load lock chamber 22 and transfers them to the processing stage B of the processing chamber 20.
In the load lock chamber 24, the processed works 10, which have been conveyed to the stage A, are transferred to the holder 28, which are set in the load lock chamber 24, one by one, by a hand 36.
The action of feeding the works 10 from the load lock chamber 22 and the action of conveying the works 10 from the stage A to the load lock chamber 24 are synchronously performed with the processes performed in the stages C-F of the processing chamber 20. Namely, the work 10 fed to the stage B is processed in the stages C-F, then conveyed from the stage A to the load lock chamber 24.
In the apparatus having the processing chamber 20 and the load lock chambers 22 and 24, the works 10 are sequentially fed to the processing chamber 20, and the processed works 10 are also sequentially carried out, so that a plurality of the processes can be efficiently performed.
When all of the works 10, which have been fed to the load lock chamber 22, are processed, the works 10 are newly fed to the load lock chamber 22 and the processed works 10 are carried out from the load lock chamber 24. However, it takes a long time to exchange the works 10 in the load lock chambers 22 and 24.
In a typical case, a total time to exchange the works 10 in the load lock chamber 22 is about 100 seconds. The time length includes: (1) 20 seconds to return the inner pressure of the load lock chamber 22 to the atmospheric pressure; (2) 30 seconds to feed and carry out the works 10; and (3) 50 seconds to close the load lock chamber 22 and reduce the inner pressure thereof.
On the other hand, it takes several seconds to 10 seconds to perform the processes in the processing stages of the processing chamber 20. For example, it takes about 360 seconds to completely plasma-process 25 semiconductor wafers. According to the time of plasma-processing, i.e., 360 sec., and the time of exchanging (feeding and carrying out) the works 10, i.e., 100 sec., the time of exchanging the works 10 accounts for about 20% of the total processing time.
By shortening the time of processing the works 10 in each of the processing stages, the time of exchanging the works 10 highly influences production efficiency. To improve the production efficiency, it is very important to highly efficiently feed and carry out the works 10.